The present invention relates generally to electro-acoustic transducers and, more particularly, to flextensional transducers and methods of using flextensional transducers.
Flextensional transducers are known for their traditional use as high-power, low-frequency ultrasound sources in underwater acoustic applications. Among other end uses, they have been adapted for use as low-power, low-frequency transducers for medical ultrasonic applications. Flextensional transducers currently used in such medical ultrasonic applications generally include a solid piezoelectric ceramic disk arranged between a pair of metal endcaps. When the ceramic disk is energized with a current of alternating polarity, the ceramic disk expands and contracts radially in a sinusoidal manner. This radial expansion and contraction is mechanically transferred to the endcaps, causing the endcaps to flex outwardly or inwardly so as to amplify the mechanical motion generated by the ceramic disk. In turn, the rapid sinusoidal flexing of the endcaps generates ultrasonic sound waves that are emitted outwardly from each of the endcaps.
Flextensional transducers are structurally symmetric in both axial and radial directions of the ceramic disk, and thus radiate sound waves equally in two opposed directions, outwardly from each endcap. This results in waste of sound energy in applications where radiation is required to be emitted in only one direction. Furthermore, such transducers have been encapsulated in epoxy or polymers in order to create arrays of elements to increase the total area for radiation of sound energy. Such encapsulated transducers are “floating” within the encapsulation and not mounted or otherwise secured to a support structure. This mounting arrangement may result in excessive vibration of, and stress on, conductive wiring connected to the transducer.
Improved flextensional transducers and methods of using flextensional transducers are needed.